Marine propulsion system



Nov. 3, 1964 H. J. BUTTNER MARINE PRoPULsIoN SYSTEM 5 Sheets-Sheet l Filed April 25, 1961 nuff" Nov. 3, 1964 H. J. BUTTNr-:R 3,155,071

MARINEPROPULSIONSYSTEM Filed April 25, 1961 5 sheets-sheet 2 Nov. 3, 1964 H. J. BUTTNER 3,155,071

MARINE PROPULSION SYSTEM Filed April 25, 1961 5 Sheets-Sheet 5 F/G 6A f TO TROTTLE -OPEN -62 BOTH PUMPS E@ BOTH PUMPS REvERsE c: FORWARD HG 6D F/G 6B 70 L LEFT RIGHT REVERSE BOTH PUMPS REVERSE RIGHT PUMP f-REVERSE LEFT PUMP TO LEFT TO RIGHT Nov. 3, 1964 H. J. BUTTNER 3,155,071

MARINE PRoPULsIoN SYSTEM Filed April 25, 1961 5 sheets-sheet 4 Nov. 3, 1964 H. J. BUTTNER 3,155,071

MARINI: PRoPULsIoN SYSTEM Filed April 25, 1961 5 sheets-sheet 5 F/a /0A um 4U @L c /0/ gf A WATER L|NE l WLEER [if United States Patent Oftice 3,155,011 Patented Nov. 3, 1964 3,155,071 MARENE PRFULSIN SYSTEM Horace Il. Buttner, New Canaan, Conn., assigner to Textron nc., Eyram, Conn., a corporation of Rhode Island Fiied Apr. 25, 1961, Ser. No. 105,419 S Claims. (Cl. 115 16) The present invention relates to marine propulsion systems, and particularly to jet propulsion for boats. The term boat is used in a broad sense to include both surface and sub-surface craft. While jet propulsion systems in accordance with the invention are applicable to all kinds of boats, they are particularly advantageous for boats of the general category referred to as pleasure craft and the invention is accordingly illustrated installed in a boat of this kind.

Jet propulsion has important advantages over conventional propeller drive. As propellers are normally below the shear line of the boat hull they are subject to damage by striking logs, rocks or other submerged objects. Moreover, when persons are in the water near the boat, for example when swimming or water-skiing, there is danger of serious injury through being struck by a propeller. Trouble is also experienced with weeds, sh lines, ropes, etc. becoming wound on the propeller and the adjacent propeller shaft. These disadvantages are avoided with jet propulsio-n.

The present invention is directed to an improved jet propulsion system having high eiciency and providing greater maneuverability. A further important advantage of the system in accordance with the invention is that the entire installation is exceptionally compact and occupies minimum space in the boat. The combined engine and propulsion unit is preferably installed in the stern of the boat or in a separate hull or pod removably mounted on the stern of the boat. The latter mode of installation provides the feature of removability for servicing characteristic of outboard motors. However, in comparison with outboard motors, particularly those with higher horsepower, the propulsion system in accordance with the present invention is materially more etlicient and is safer, not only because of eliminating the propeller, but also by lowering the center of gravity.

The marine propulsion system in accordance with the invention comprises a motor mounted in the hull with its drive shaft extending athwartship. A Water pump is preferably mounted at each end of the motor and has a rotor driven by the drive shaft, one pump being connected with one end of the shaft and the other pump connected with the other end. Each pump has an intake below the water line and a discharge that is directed rearwardly so that jets of water issuing rearwardly from the pumps exert a forward thrust on the boat. To reverse the boat the direction of the jets is reversed either by reversing the direction of discharge of the pumps r by redirecting the discharge. Means is provided for individually controlling the discharge from the two pumps to vary the direction of the resultant thrust on the boat and thereby provide steering. Although it has only a single engine, the boat has the desirable steering characteristics of a twin-screw craft. For example,the thrust of one pump can be reversed while the other acts forwardly to provide sharp turning or to turn the boat without rearward or forward movement. Moreover, the control, including reverse drive, is achieved without reversing the direction of drive of the pumps so that no shifting of gears or clutches is required and it is not necessary to bring the engine to idling speed when changing from forward to reverse.

Further characteristics of the Iinvention and its many advantages will appear more fully from the following description of the preferred embodiments of the invention shown by way of example in the following drawings in which FIG. 1 is a schematic plan showing a marine propulsion system in accordance with the inventioninstalled on a boat;

FIGS. 2 and 3 are sections taken respectively on the lines 2 2 and 3 3 in FIG. 1;

FIG. 4 is a section taken approximately on the line 4 4 in FIG. 2;

FIG. 5 is'a section taken approximately on the line 5 5 in FIG. 4;

FIGS. 6A, 6B and 6C illustrate schematically a unitary control system 6A being a side view, 6B a rear view and 6C a plan and wiring diagram;

FIGS. 6D and 6E are enlarged views of one of the switches shown in FIG. 6C in different yoperatvie positions;

FIGS. 7, 8 and 9 illustrate another embodiment of the pump unit and associate controls, FIG. 7 being a side View partially in section, FIG. 8 a front View and FIG. 9 a fragmentary section on the line 9 9 in FIG. 7;

FIG. 10 is a side view partially in section of another embodiment of pump and associated controls;

FIG, 11 is a side view of another pump unit.

In FIG. 1 there is shown a boat 1 having a bow portion 2 and a stern 3. The boat is propelled by a propulsion system comprising a motor 5 mounted transversely of the boat and two pumps 6a and 6b mounted respectively at opposite ends of the motor and both driven from the engine drive shaft. Each of the pumps has an intake 7 extending below the water line of the boat and `a discharge 8 which is directed rearwardly above the water line and discharges the water as a high velocity jet, the reaction force of which exerts a forward thrust for propelling .the boat.

The propulsion unit comprising the motor 5 and pumps 6a, 6b is mounted in the stern portion of the boat and may be either in the stern 3 of the main boat hull or as illustrated by way of example in FIG. 1, 2 and 3, in an auxiliary hull or pod which is removably mounted on the transom 9 of the main boat hull floating structure of the boat. The mounting of the pod 10 provides not only removability, but also adjustability both vertically and angularly. Tracks 11 of channel cross section on the forward wall of the pod are vertically slidable on swinging brackets 12 which are fixed on a hollow shaft 13 rotatably supported by spaced brackets 14 mounted on the transom of the boat. The shaft 13 is rotatable to change the angular position of the pod by means of a worm wheel 15 which is xed on the shaft and rotatable by means of a worm rotatably mounted on the support bracket 14 and turned by a small handcrank 16. Vertical adjustment of the pod is effected by means of racks 17 xed on the tracks 11 and meshing with pinions 18 fixed on a shaft 19 that extends through and is rotatably supported by the hollow shaft 13. The shaft 19 is rotatable by means of a worm gear 21 which is iixed on the shaft 19 and rotated by a worm which is rotatably mounted on the bracket 12 and turned by a small handcrank 22. The supporting brackets 14 are removably mounted on the transom 9 by means of screw clamps 23 so that the entire unit comprising the 'pod 10, engine 5, pumps 6a, 6b and associated mechanism is removable from the boat as a unit for storage, transportation or servicing.

The pod 10 has a central engine compartment 25 having watertight sides and bottom. and a hinged cover'26. The pumps 6a, 6b are housed in side compantments 27 which need not be watertight. Additional compartments 28 and 29 provide fuel storage and space for a battery and any other accessories so that the power unit in the pod is entirely self contained. Whether the propulsion unit is in a separate pod as shown or mounted directly in the stern portion of the boat the transverse position of the motor and the mounting of the pumps at the opposite ends of the motor provide a compactassembly requiring a minimum of boat space. Moreover, the use of two pumps providing laterally spaced jets which are individually controllable affords greater maneuverability of the boat.

The motor 5 is any suitable power plant providing adequate power for driving the boat at the desired speed and is preferably light weight and compact. It can, for example be an electric motor or an internal combustion engine of in-line, V opposed cylinder or other suitable configuration. As shown by way of example from the drawings the motor is a four cylinder vertical internal combustion engine having a crankshaft 30 extending from both ends of the engine and a fly wheel 31. By reason of the .inertia etfect of the pumps mounted on opposite ends of the crankshaft the fly wheel can, if desired, be omitted. The engine 5 is provided with suitable accessories and controls including speed control. However, no transmission gears, reversing gears or clutches are required. Suitable vibration mounts are provided for the engine and the engine compartment is preferably sound insulated. If the engine is water cooled, the cooling water is preferably supplied by connections (not shown) with one or both of the pumps 6a, 6b so that no separate water pump is required. Opposite ends of the engine drive-shaft extend through opposite side walls of the engine compartment. Suitable sealing glands 32 are provided to keep the compartment watertight.

The two pumps 6a and 6b are mounted directly on opposite ends of the engine drive-shaft and are identical with one another except that one is a mere reversal of the other. The pumps are thus symmetrical with respect to the central vertical plane of the boat. Each pump comprises a rotary impeller 34 which is fixed on and driven by the engine drive-shaft, a rotatable inner casing 35 and a stationary outer casing 36. The outer casing 36 is concentric with the impeller and has two discharge passageways or nozzles, namely, the aforementioned discharge 8 through which water is directed rearwardly so as to propel the boat in a forward direction and a discharge passageway or nozzle 38 through which water is directed forwardly so as to propel the boat in a rearward or reverse direction.` For convenience, the nozzles S are herein referred to as the forward nozzles and the nozzles 38 as reverse nozzles. The inner casing 35 is of involute shape with a discharge passage 39 and is mounted so as to be rotatable about the central axis of the pump so as to bring the discharge passage 39 of the inner casing into registry with the forward discharge nozzle 8 as shown in FIG. 4 or in registry with the reverse nozzle 38. Suitable seals are provided between the stationary outer casing 36 and the rotary portions of the pump to prevent excessive leakage. However, a completely watertight seal is not required since, as will be seen in FIG. 3, the pump compartments are partially open, a watertight barrier being provided between the pump compartments and the engine compartment. The forward nozzle 8 extends rearwardly through the rear wall of the compartment while the reverse nozzle 38 extends forwardly and downwardly through the bottom but does not project appreciably below the bottom of the compantmentz. When the engine and pump assembly are located in a compartment as il lustrated in FIGURES l to 5, the rear wall of the compartment is considered as the rear wall of the boat structure.

Each pump is further provided with an intake pipe 7 which opens below the bottom of the compartment and connects axially to the pump. The intake pipe 7 is retractable so as to clear any obstruction over which the boat passes. For this purpose, the intake pipe 7 is L mounted so as to be swingable about the axis of the pump between an operative position in which the intake pipe projects below the bottom of the boat as shown in FIGS. 2 and 3 and a retracted position in which the lower end of the intake pipe is above the bottom of the boat. A hook latch 40 pivoted at 41 engages a detent portion 42 on the intake pipe to hold the pipe in operative posiftion. The latch has a ring shaped trigger portion 43 which extends downwardly from the pivot and normally lies in a selected distance in front of the leading edge of the intake pipe. The ring 43 is of approximately the same diameter as Vthe intake pipe so as not to interfere with the llow of water. If the trigger portion 43 meets an obstruction, the latch is swung in a clockwise direction as viewed in FIG. 3 so as to release the intake pipe and permit it to swing rearwardly and upwardly out of the way of the obstruction. The leading edge of the intake pipe lies substantially in or rearwardly of a vertical plane passing through the axis of the pump so that as the intake pipe swings rearwardly it also moves up-k wardly. When the boat is stopped after an obstruction has been encountered the intake pipe will swing back to operative position by gravity. A light spring may be provided if desired to assist the return of the intake pipe to operative position.

The pumps are preferably of centrifugal or mixed flow type with an axial intake and a tangential discharge. By mixed ow is meant that the initial acceleration is axial followed by radial acceleration of the water in the pump. The pumps are of high efiiciency and the citiciency of the system is further increased by the use of short straight discharge nozzles and a forwardly facing intake pipe extending below the bottom of the boat to take advantage of impact velocities when the boat is moving forwardly.

Provision is made for controlling the pumps to provide for both steering and reversal of motion. Forward and reverse drive are provided by positioning the inner casing 35 of the pump so as to bring its discharge 39 into alignment with the forward nozzle 8 or the reverse nozzle 33. By reason of the reaction forces the *inner casing of the pump tends to turn in a counterclockwise direction as viewed in FIG. 4. It is held in forward and reverse position respectively by retractable latches 45 and 46 releasably engaging an abutment 47 on the inner pump casing. The latches 45 and 46 are retractable respectively by solenoids 48 and 49. Latch 45 is herein referred to as the forward latch while latch 46 is referred to as the reverse latch. lf the forward latch is retracted when the pump is in forward drive position as shown in FIG. 4 the inner casing 35 rotates in a counterclockwise direction until the abutment 47 engages reverse latch 46.

Directional control in forward drive is provided by means regulating the discharges of the respective pumps and also varying the direction of discharge. As illustrated in FIGS. 1 to 5 the control means comprises throttle members 59a and Silb controlling the discharges of pump 6a and 6b respectively. Each of the throttle members is swingable about a Vertical pivot on the inboard side of the discharge passage between an open position as shown in solid lines in FIG. l in which it does not obstruct discharge of the pump to a closed position in which the discharge passage is closed. In intermediate positions the throttle member laterally deflects to a greater or lesser extent the jet of water issuing from the discharge nozzle. Suitable linkage or other mechanism is provided for controlling the positions of the throttle members. For movement straight ahead both throttle members are in fully open position. To turn the boat toward the right, the right hand throttle member 50h is swung toward closed position. The jet of water from pump 6b is thereby deflected toward the right and the reaction force tends to move the stern of the boat to port so that the bow of the boat is turned to vthey are not already there.

starboard. If the throttle member Sb is moved all the way to closed position the right hand jet is shut of and the boat is turned to starboard by the action of the left hand jet. If it is desired to turn the boat still more sharply, the right hand pump is reversed so as to discharge through the reverse nozzle 38. A strong turning moment is thereby developed by the forward thrust of the left jet and the rearward thrust of the right jet.

Steering in reverse direction is provided by throttles 52a and 52b in the discharge nozzles of the pumps 6a and 6b respectively. Control means is provided for actuating the throttles selectively so as to control the relative force of the two jets. If it is desired to swing the bow of the boat to starboard while in reverse, the throttle 52a is closed or partially closed while the throttle 52b is left open so as to provide a greater rearward thrust on the starboard side of the boat. If sharper turning is desired one pump is left in reverse While the other is shifted to forward. As changing from forward to reverse is elfected merely by permitting the inner casing of the pump to turn from one position to the other, no gear shifting or declutching is required and the change can be made while the engine is still operating under power. Excellent maneuverability of the boat is thereby provided.

A control system shown schematically in FIGS. 6A to 6E provides for control of the boat by means of a single stick 55 which is swivelly mounted at a fulcrum 56 for movement forward and aft and also laterally. In FIGS. 6A to 6C the control stick is shown in a central neutral position. Control of engine speed is provided by spaced parallel bars 57 and 58 positioned respectively above and below the fulcrum point of the stick 55 and carried by a slidably mounted bar 59 connected to the throttle or other engine speed control. A spring 66 tends to move the bars 57, 58 toward the stick 55 to an idle position in which both bars are spaced a selected distance from the stick when in central position. When the upper end of the stick 55 is moved either forwardly or rearwardly it engages one or other of the bars 57, 58 to move the throttle progressively toward open position.

Forward and reverse movement of the boat is controlled by parallel bars 61 and 62 disposed respectively aft and forward of a lower end portion of the stick. When the forward end of stick 55 is moved forwardly the lower end moves rearwardly into engagement with bar 61 which controls the pump discharge so as to provide a rearwardly directed jet for propulsion in a forward direction. While mechanical means may be provided for connecting bars 61 and 62 with the mechanism controlling the direction of the jet, suitable electrical connections are shown by way of example in FIGS. 6C to 6E. Each of the bars 61, 62 is provided at each end with a telescopically slidable extension 63, 64 carrying at its outer end an electrical Contact bar 65, 66. A spring 67 biases each of the extensions 63, 64 against a stop in an inner position. When the bar 61 is moved rearwardly by forward movement of the upper end of control stick 55, the contact bars 65 at both the left and right side are moved into engagement with stationary contacts 68 and 69 and thereby close a circuit energizing the reverse solenoids 49 of both pumps so as to retract the latches 46 and thereby permit the inner casings of the pump tomove to forward position, if

In a similar manner rearward movement of the upper end of stick 5S moves the control bar 62 forwardly and thereby brings contact bars 66 into engagement with contacts 70 and 71 to energize the solenoids 48 of both pumps to retract the forward latches and thereby permit the pumps to turn to reverse position. Movement of the control stick in Aeither forward or reverse direction progressively opens Steering is obtained by moving the stick laterally in the direction it is desired to turn. Longitudinally extending parallel bars 73 and 74 disposed on opposite sides of the lower end of the control stick 55 are connected respectively to the jet discharge throttles 50a and 50!) and also to the reverse discharge throttles 52a and 52h. When the upper end of the control stick is moved toward the right, the throttles of the right hand pump are progressively moved toward closed position causing the boat to turn toward the right as explained above. Movement of the upper end of the control stick toward the left causes the boat to turn toward the left in similar manner. If sharper turning is desired or it is desired to turn without substantial forward or rearward movement, the stick is moved farther toward the right or left so as to bring it into engagement with one or another of longitudinally extending parallel bars 75 and 76 which in their normal positions are spaced further apart than bars 73 and 74. Each of the bars 75, 76

is connected by a rod 77 to a cross head comprising contact bars 78 and '79. When the upper end of the control stick is moved toward the left a predetermined distance so as to bring the lower end of the stick into engagement with the bar '75 (FIG. 6C) and move the bar 75 toward the right, contact bar 78 is brought into engagement with contacts 68 and 71 (FIG. 6E) and contact bar 79 is brought into engagement with contacts 69 and '70. At the same time, contact bar 65 is moved endwise out of engagement with contact 68. The reverse solenoid 49 is thereby de-energized to permit the reverse latch to move into operative position while engagement of contact bar 78 with contacts 63 and '71 energizes the forward solenoid 48 so as to withdraw latch 45 and permit the inner casing of the pump to turn to reverse position. The left hand pump is thus reversed while the right hand pump continues to operate in forward position thereby turning the boat sharply to the left. Likewise, when the boat is in reverse, movement of the control Istick a selected distance to one side or the other causes the respective pump to be changed to forward position so as to provide the turning desired. It will thus be seen that the single stick 55 provides full control of the boat including forward or reverse movement, speed and steering, including selective reversal of one pump or the other for sharp turning.

In FIGS. 7 to 9 there is shown another pump construction including reversing and steering controls. A pump 80 has a stationary casing S1 having a tangential discharge opening 82. An intake pipe 83 is rotatably mounted for retraction like the intake pipe 7 shown in FIGS. l to 5. The pump is mounted in the boat so that the discharge 82 is directed rearwardly, to provide forward propulsion of the boat. Reverse drive is obtained by means of a flexible deflecting strip 84 made for example of stainless steel and slidable in a track 85 which extends partially around the pump casing and along the peripheral edges of rearwardly extending wings 86 of the end walls of the pump casing. The deector 84 is slidable from the position shown in FIG. 7 for forward drive to a position in which the detlector is positioned in the rearward portion of the track 85 so as to dellect the discharge stream of the pump downwardly and forwardly and thereby provide a rearwardly directed thrust. Suitable control means is provided for moving the deector from one position to another. In FIGS. 7 and 8 the control means is shown as comprising a transverse bar 87 at one end of the deflector having projected end portions received in slots in radially extending arms 88 which are provided at opposite ends of the pump and are rotatable about the pump axis. Suitable linkage or other mechanism is provided for swinging the` arms about their axis and thereby sliding the defiector 84 in the guiding track 85. Instead of being moved all the way from forward to reverse position the deector 84 may be moved partway so as to direct the jet downwardly and thereby provide a selected upward force, for example, to trim the boat or lift it oit a sand bar.

Steering is provided by a throttle member 90 on discharge of each pump. The throttle is swingable between open and closed positions by suitable control mechanism including an arm 91. By closing or partially closing the throttle on the discharge of one pump while leaving the other open the boat can be caused to turn in either direction. The throttles are elfective in reverse as well as in forward drive. Moreover, turning can be effected by selectively reversing the discharge of one pump by means of the deector 84.

In FIG. l() there is shown another form of pump having a casing 9S with a discharge nozzle 96. The entire pump casing including the discharge nozzle is rotatable about the axis of the pump impeller so as to position the pump casing with the discharge nozzle 96 irected rearwardly for forward propulsion, forwardly for rearward propulsion or downwardly for lift. The position of the pump casing is controlled by abutments 97a, 97h and 97C on the casing engageable respectively with retractable latches which are shown schematically and designated 98a, 98h and 98e respectively. The latches are operated mechanically, hydraulically or electrically as shown for example in FIGS. l to 5. With the latch 93a in operative position and latches 98h and 98e in retracted position the pump casing 95 will rotate in a clockwise direction until the abutment 97a engages the latch 98a thereby positioning the pump for forward propulsion. The pump is similarly positioned in its other positions by selective operation of the latches.

Steering is provided by a throttle 100 provided in the intake of each pump and selectively controlled by means of suitable linkage 101 or other operating means. By closing or partially closing the throttle in the intake of one pump While the other is left open the boat can be turned as desired. Turning can also be effected by reversing one vpump while the other is left in forward position. The intake pipe of the pump comprises a stationary portion 102 which extends down to and opens through the bottom of the boat and an arcuate movable portion 103 which is telescopically slidable into and out of the stationary portion. The telescopic portion 103 is retractable to clear any obstruction thatmay be encountered. It can also be positioned to provide ya variable etective intake opening. A maximum intake opening is provided when the movable section 103 is fully extended as shown in FIG. 10. When the movable portion 103 is partially retracted its projected area is reduced. A variation of the projected yarea. is desired for example at different speeds. When the boat is travelling at low speed it is desirable to have the movable intake pipe section fully extended. As the speed increases the movable section 1h31 is progressively retracted to reduce the projected area. Suitable means is provided for selectively positioning the movable intake section 103. As illustrated schematically and by way of example in FIG. l a small pinion 104 driven by an electric motor S is engageable with gear teeth 106 provided on the movable section 103. A suitable slipclutch or shear pin is provided to permit rapid retraction of the section 103 in the event it strikes an underwater obstruction.

In FIG. ll there is shown .another form of pump having a stationary pump casing 110 with a tangentially directed discharge nozzle 111. The impeller ofthe pump rotates in a clockwise direction as viewed in FIG. 11 and the discharge nozzle is hence at the bottom of the pump in such position thatit discharges below the water line of the boat. The discharge of each pump is con- -trolled by a throttle 112 .actuated by suitable linkage 113 or other mechanism. Steering is effected by selective actuation of the throttles as described above. Semicylindrical deflectors 114 swingable about pivots 115 from a forward position as shown in solid lines to a reverse position as shown in bnoken lines. When in reverse position the deectors 114 extend below the bottom of the boat. In the event of sudden engine failure while the boat is travelling at high speed the boat can be slowed down by swinging the deectors 114 to reverse position so as to increase the drag of the boat. The deliectors 114 are movable from one position to another by suitable linkage or other control mechanism. The pump is provided with lan intake pipe 117 which is retractable by swinging about an axis coinciding with the axis of the impeller. The intake pipe 117 is normally held in the position shown by a spring 118.

It will be seen that the propulsion system in accordance with the present invention with a single engine provides the exibility and maneuverability afforded by a boat having two engines and two screws. In fact, even greater maneuverability is provided since it is possible to shut olf either or both jets or to reverse the thrust of either or both jets substantially instantaneously without the need of any gear shifting or declutching or of bringing the engine to idling speed.

While several embodiment-s of the invention have been illustrated in the drawings and herein particularly described, it will be understood that the invention is in no way limited yto these embodiments. Features illustrated in each embodiment are mutually interchangeable with other embodiments insofar as they are applicable. Still other modifications within the scope of the appended claims will be apparent to those skilled in the art.

What I claim and desire to secure by Letters Patent is:

1. A jet propulsion system for a boat having a floating structure with a bottom, side walls, a transverse rear wall and a longitudinal axis, comprising a motor mounted in said oating structure adjacent said rear wall and having a drive shaft disposed transversely of said longitudinal axis .and extending from opposite ends of said motor, a rotary pump at each of the opposite ends of the motor and having a rotatable casing having a discharge opening and a rotor connected to and driven by said drive shaft, each of said pumps having an intake passage opening through the bottom of said structure and two discharge passages, a lirst of said discharge, passages extending from said pump directly through said rear wall and discharging a jet rearwardly of said boat whereby the discharge of water from said pumps exerts a forward thrust on said boat, the second of said discharge passages opening through the bottom of the boat and directed forwardly whereby the discharge of water from the pumps exerts a rearward thrust on the boat, the discharge passages of one pump being spaced laterally from those of the other pump, each `said pump casing being rotatable between a forward drive position in which discharge of water from said opening is through said first discharge passage directed rearwardly of said boat and a reverse drive position in which discharge of water from said opening is through said second discharge passage directed forwardly of said boat, unitary means for co-ordinating the control of both of said pumps, said system including said motor and pumps being disposed in a space between said side walls and adjacent said rear wall having Va lesser extent in the direction of said longitudinal axis than in a direction transverse of said longitudinal axis.

2. A marine propulsion system according to claim 1, in which said control means comprises means for controlling the positions of said pump casings selectively to posi-tion both pump casings in forward drive position, both pump casings in reverse drive position and either pump casing selectively in forward drive position while the other of said pump casings is in reverse drive position to exert a turning moment on said boat.

3. A jet propulsion system for a boat having a floating structure with a bottom, side walls, a transverse rear wall :and a longitudinal axis, comprising a motor mounted in said oating structure adjacent said rear wall and having a drive shaft disposed transversely of said longitudinal axis and extending from opposite ends of said motor, a rotary pump at each of the opposite ends of the motor and having a casing and a rotor connected to and driven by said drive shat, each of said pumps having an axial intake and a peripheral discharge, an intake passage for each of said pumps opening through the bottom of said structure adjacent said pump and curvin7 upwardly and then laterally into said inlet, and an individual low resistance discharge passage extending from said pump directly through said rear wall and discharging a jet rearwardly of said boat, whereby the discharge of water from both of said pumps exerts a forward thrust on said boat, said discharge pass-ages being laterally spaced, means for individually controlling the discharge of each of said pumps to vary the resultant thrust and thereby impart 'a steering moment for turning said boat, said control means comprising vane means swingable about a vertical pivot axis disposed at the side of said discharge passage and means for swinging said vane means about its axis to deflect 'the discharge laterally outwardly and swinging said vane means further progressively to close said discharge passage and thereby attenuate said discharge to produce a steering moment on said boat by the combined action of selective lateral deiiection of said jets and selective attenuation of said jets and unitary means for co-ordinating the control of both of said jets, said system including said motor, pumps, intake :and discharge passages being disposed in a space between said side walls and adjacent said rear wiall having a lesser extent in the direction of said 1ongitudinal axis than in a direction tranverse of said longitudinal axis.

4. A marine propulsion system according to claim 3, in which said intake has a forwardly facing intake opening for producing a ram eect on the pump intake by the velocity of the boat through the water when moving forwardly and in which means is provided for varying the effective crosssectional area of said forwardly facing intake opening and thereby varying said ram effect.

5. A marine propulsion system according to claim 3, in which said intake comprises conduit means extending beyond said hull into the water and in which said conduit means is retractable to clear any obstruction that may be encountered by said conduit means.

6. A marine propulsion system according to claim 5, in which a latch releasably holds said conduit means in extended position and in which trigger means connected with said latch is positioned in front of said conduit means to be engageable by an obstruction to release said conduit means.

7. A marine propulsion system for a boat having a hull, comprising a motor mounted in the rear portion of said hull and having a drive shaft extending athwart said hull and extending from opposite ends of said motor, means for controlling the speed of said motor, a pump mounted at each end of said motor and having a rotor connected to and driven by said drive shaft, both of said pumps being driven concurrently by said motor, each of said pumps having an intake below the Water line of said hull and individual, low resistance discharge means directed rearwardly of said hull whereby the discharge of water from both of said pumps exerts a forward thrust on said hull, means for reversing the direction of discharge of Water from said pumps to exert a rearward thrust on said hull, steering means for controlling the discharge of water from said pumps to vary the direction of the resultant thrust produced by said discharge and unitary control means comprising a single control member connected to and movable to control said motor speed controlling means, said reversing means and said steering means to thereby control the direction of movement, the reversal of movement and the rate of movement of the boat.

8. In combination with a motor boat having a floating structure with a bottom, side walls, a rear wall and a longitudinal axis, an internal combustion engine having a housing and a drive shaft extending from both ends of said housing, means mounting said engine in said floating structure adjacent said rear wall with the drive shift of said engine extending transversely of said longitudinal laxis, two centrifugal pumps each having an axial intake and peripheral discharge and an impeller rotatable in said casing, means mounting said pumps at opposite ends of said engine housing with the impellers of said pumps coaxial with and driven by said drive shaft, an intake passage for each of said pumps, each intake passage opening through the bottom of the boat tol communicate with the water in which the boat is oating and curving upwardly and then laterally into said intake, a short substantially rectilinear discharge passage connected with the discharge of each pump and extending through said rear wall to provide a low resistance path directing water rearwardly from said boat to provide a forwardly directed reaction force for propelling said boat forwardly and means for individually controlling the discharge of each of said pumps to vary the resultant thrust and thereby impart a steering moment for turning the boat, said control means comprising vane means swingable about a vertical pivot axis disposed at the side of said discharge passage and means for swinging said vane means about its axis to direct the discharge laterally outwardly and swinging said vane means -further progressively tio close said discharge passage and thereby attenuate said discharge to produce a steering moment on said boat by the combined action of selective lateral deilection of said jets and selective attenuation of said jets and unitary means for coordinating the control of the discharge fof both of said pumps, said engine, pumps, intake passages and discharge passages being disposed in a space adjacent said rear wall having a lesser extent in the direction of said longitudinal axis than in a direction transverse of said longitudinal axis.

References Cited in the file of this patent UNITED STATES PATENTS 141,039 Dow Iuly 22, 1873 646,391 Simmons Mar. 27, 1900 958,996 Duc May 24, 1910 1,914,038 Ouss et al. June 13, 1933 2,024,274 Campini Dec. 17, 1935 2,327,994 Briggs Aug. 31, 1943 2,356,301 Brase Aug. 22, 1944 2,664,700 Benoit Ian. 5, 1954 2,696,077 Goodman Dec. 7, 1954 2,993,463 McKinney July 25, 1961 3,007,305 Hamilton Nov. 7, 1961 3,083,530 Spence Apr. 2, 1963 

1. A JET PROPULSION SYSTEM FOR A BOAT HAVING A FLOATING STRUCTURE WITH A BOTTOM, SIDE WALLS, A TRANSVERSE REAR WALL AND A LONGITUDINAL AXIS, COMPRISING A MOTOR MOUNTED IN SAID FLOATING STRUCTURE ADJACENT SAID REAR WALL AND HAVING A DRIVE SHAFT DISPOSED TRANSVERSELY OF SAID LONGITUDINAL AXIS AND EXTENDING FROM OPPOSITE ENDS OF SAID MOTOR, A ROTARY PUMP AT EACH OF THE OPPOSITE ENDS OF THE MOTOR AND HAVING A ROTATABLE CASING HAVING A DISCHARGE OPENING AND A ROTOR CONNECTED TO AND DRIVEN BY SAID DRIVE SHAFT, EACH OF SAID PUMPS HAVING AN INTAKE PASSAGE OPENING THROUGH THE BOTTOM OF SAID STRUCTURE AND TWO DISCHARGE PASSAGES, A FIRST OF SAID DISCHARGE, PASSAGES EXTENDING FROM SAID PUMP DIRECTLY THROUGH SAID REAR WALL AND DISCHARGING A JET REARWARDLY OF SAID BOAT WHEREBY THE DISCHARGE OF WATER FROM SAID PUMPS EXERTS A FORWARD THRUST ON SAID BOAT, THE SECOND OF SAID DISCHARGE PASSAGES OPENING THROUGH THE BOTTOM OF THE BOAT AND DIRECTED FORWARDLY WHEREBY THE DISCHARGE OF WATER FROM THE PUMPS EXERTS A REARWARD THRUST ON THE BOAT, THE DISCHARGE PASSAGES OF ONE PUMP BEING SPACED LATERALLY FROM THOSE OF THE OTHER PUMP, EACH SAID PUMP CASING BEING ROTATABLE BETWEEN A FORWARD DRIVE POSITION IN WHICH DISCHARGE OF WATER FROM SAID OPENING IS THROUGH SAID FIRST DISCHARGE PASSAGE DIRECTED REARWARDLY OF SAID BOAT AND A REVERSE DRIVE POSITION IN WHICH DISCHARGE OF WATER FROM SAID OPENING IS THROUGH SAID SECOND DISCHARGE PASSAGE DIRECTED FORWARDLY OF SAID BOAT, UNITARY MEANS FOR CO-ORDINATING THE CONTROL OF BOTH OF SAID PUMPS, SAID SYSTEM INCLUDING SAID MOTOR AND PUMPS BEING DISPOSED IN A SPACE BETWEEN SAID SIDE WALLS AND ADJACENT SAID REAR WALL HAVING A LESSER EXTENT IN THE DIRECTION OF SAID LONGITUDINAL AXIS THAN IN A DIRECTION TRANSVERSE OF SAID LONGITUDINAL AXIS. 